Remote control system



Nov. 10, 1942. P, CRAGO 2,301,376

7 REMOTE CONTROL SYSTEM Filed July '10, 1941 INVENTOR Paul H Una g0 Q/w/JWM "YA HIS ATTORNEY Patented Nov. 10, 1942 UNITED STATES PATENT OFFECE REMOTE CONTROL SYSTEM Paul H. Crago, Wilkinsburg, Pa., assignor to The Union Switch & Signal Company, Swissvale, Pa., a corporation of Pennsylvania Application July 10, 1941, Serial No. 401,753

4 Claims.

My invention relates to a remote control system, and more particularly to a remote control system for railways.

In remote control systems for railways continuous control and indication of switches, signals and other trafiic governing units are provided. The control station or oilice and the switches and signals are usually relatively far apart and for economy of apparatus and circuits it is desirable that the control and indication influences for the different switches and signals be transmitted in each case over a single line circuit. The track layout of an interlocking is in many'instances unbalanced as to th number of switches and signals. When such an interlocking is controlled from a remote office through the medium of a remote control system, extra line circuits and apparatus may be required because of the unbalanced layout and such extra circuits and apparatus add to the initial cost and to the upkeep of the system.

In view of the above circumstances in remote control systems for railways, a feature of my invention is the provision of a remote control system for railways incorporating novel and improved means wherewith each traffic governing unit of an interlocking is continuously controlled and indicated over a control line circuit including a control line wire and a common line wire, the common line wire serving as one side of several such control circuits. A traflic governing unit as referred to above, may consist of a single switch or of one signal, or of two or more related switches that can be operated together, or of two or more related signals that can be selectively incorporating novel apparatus by Which the sys- 1 tem is made flexible for application without extra line circuits to an interlocking having an unbalanced layout of switches and signals.

Again, a feature of my invention is the provision of novel means for remote control systems wherewith not only the normal and reverse positions of a switch are indicated but indications of switch in transit and switch locked are provided as well as an indication of a train in the vicinity of such switch.

Other features, advantages and objects of my invention will appear as the specification progresses.

Theabove features and advantages of my invention are obtained by providing each traffic governing unit of an interlocking with a control line circuit which extends between the controlling office and a station located adjacent the interlocking, and which line circuit terminates in four branch circuits at each of the two locations. That is, in the remote control of an interlocking, each traflic governing unit which may consist of a single switch or of one signal, or of a pair of related switches or of two or more related signals, is provided with a control line circuit, one wire of which serves as a common wire for several of such circuits. In each such control line circuit, two of the four branch circuits at the oilice and at the station function in the receiving of current, and the other two branch circuits at the office and at the station function in the sending of current. A

Each such receiving branch circuit preferably includes an asymmetric unit and a'magnetica-lly biased neutral relay in series. These asymmetric units may be of any one of several difierent types and may be, for example, copperoxide rectifier elements. At the ofiice andat-the station the two asymmetric units of the two receiving branch circuits of a control circuit are disposed reverse to each other so that one receiving circuit is conditioned to pass current of one polarity only and the other receiving circuit is conditioned to pass current of th other polarity only. The magnetically biased neutral relays are of the type that respond to current of one polarity only. That is, each relay is biased magnetically as well as by gravity so that its armature is released to engage back contacts when the relay is deenergized, is held at its released position when the relay is energized by current of one polarity, and is picked up when the relay is energized by current of the opposite polarity. Each biased neutral relay is disposed in the respective receiving branch circuit so as to be picked up by current of the polarity passed by the asymmetric unit of the same receiving circuit. 1

At the ofiice and at the station each of the two sending branch circuits of each control circuit includes an asymmetric unit, the two asymmetric receiving branch circuits of the same control circuit at the other location.

At the ofiice a source of alternating current is connected to each of these control line circuits through the sending branch circuits of the respective control circuit, the sending branch circuits being selectively closed over contacts of an associated manually controlled means. The arrangement is such that at one position of the manually controlled means, the sending branch circuit of the associated control circuit eifective to pass the half cycles of one relative polarity of the alternating current is closed and the other sending branch circuit is open, and at a second position of the manually controlled means, the sending branch circuit effective to pass the half cycle of the other relative polarity of the alternating current is closed and the other one is open. Furthermore, at the oilice, the receiving branch circuit of a control line circuit effective to pass current of said one relative polarity is closed at the first position of the associated manually controlled means and the one effective to pass current of said other relative polarity is opened, and at the second position of the manually controlled means this condition of the receiving branch circuits is reversed. It follows that a receiving branch circuit at the ofiice cannot be energized by current supplied by the ofiice current source. At the ofiice the biased neutral relays associated with each control line circuit are used to govern an associated indication means, such indication means being controlled to a first or a second condition according to which one of the two relays is picked up.

At the station the magnetically biased neutral relays of the receiving branch circuits of each control circuit govern the operating circuits of an associated traffic governing unit, such trafiic governing unit being operated to a first or a second position according to which one of the two relays is picked up. A source of alternating current is also provided at the station. Contacts governed by each trafiic governing unit selectively connect the station current source to the two sending branch circuits of the associated control line circuit according to the first or second position of the traffic governing unit. Also at the station the receiving branch circuits of each control circuit are interlocked so that only one receiving branch circuit can be closed at a time.

The relationship between the contacts of the manually controlled means of a control line circuit and the contacts governed by the associated traific governing unit is such that when half cycles of one relative polarity of the alternating current source at the office are supplied to the control line circuit for controlling the traflic governing unit to its first position, half cycles of the other relative polarity of the alternating curcontrol line circuit including but one control line wire and a common line wire.

Preferably the two sources of alternating current, one at the oflice and one at the station, are connected to the same transmission line so that the two currents are of the same frequency and are in phase. However, my invention is not limited to the condition where the two sources of alternating current are of the same frequency and in phase, and the two sources may be independent. For example, each such current source may be a tuned alternator, there being provided one alternator at each of the two locations. In suchan arrangement, the frequencies of the two independent sources of alternating current are preferably markedly different from each other.

At the ofiice, one winding of a special two winding relay is preferably included in each sending branch circuit of the control circuit for each track switch for providing special switch in transit and switch locked indications of the switch, as well as to provide an indication of a train in the vicinity of the switch.

I shall describe one form of apparatus ernbodying my invention, and shall then point out the novel features thereof in claims.

The accompanying drawing is a diagrammatic view showing one form of apparatus embodying my invention when used for remote control of an interlocking having an unbalanced layout of switches and signals.

Referring to the drawing, the diagram in the upper right-hand portion of the drawing designates an interlocking comprising a crossover 3 extending between an eastbound track ET and a westbound track WT. The eastbound track ET is formed by the usual insulated rail joints with a detector track section 2T, and the westbound track WT is formed with a detector track section 4T, these two track sections 2T and 4T extending beyond the limits of the crossover as is customary in such track layout. Each track section ET and 4T is provided with a track circuit which includes a track relay designated by the reference character R, plus a prefix corresponding to the reference character of the section, the relarent source at the field station are passed to the control line circuit for indicating the first position of the traiiic governing unit, and when half cycles of the other relative polarity of the alternating current source at the ofiice are supplied to the control circuit for controlling the traffic governing unit to its second position, half cycles of said one relative polarity of the alternating current source at the'station are supplied to the control circuit for indicating the second position of the traflic governing unit. It is to be seen therefore that by such use of the relative polarities of the half cycles of the two sources of alternating current, a traffic governing unit is continuously controlled and indicated over a tionship of each track relay with its section being indicated by a dash line.

In accordance with standard practice, signals R2 and L2 are located at the opposite ends of the track section 2T for governing traffic through the section, signal R2 being provided with two mechanisms RZA and B2B mounted on the same mast, and signal L2 being provided with but one mechanism. In like manner, signals L4 and R4 are located at the opposite ends of track section 4T for governing trafiic through that section, signal Lo comprising two signal mechanisms LdA and L4B, and signal R4 having but one mechanism.

Additional approach signals would be provided in accordance with standard practice, but such additional signals are not shown since they are not required for a full understanding of my invention. The type of signal mechanism used is immaterial, and may be any one of the several well-known forms.

The two track switches of crossover 3 are preferably operated by power switch machines SMI and 8M2. The type of switch machines used is also immaterial and they are shown by the symbol commonly used to indicate such power switch machines. It is sufficient for the instant application to point out that each switch machine SMI and SM2 includes a reversible motor and a mechanism (not shown) of such nature that when the motor is 'supplied'with current over one operating circuit the mechanism is operated as required to move the associated track switch to one extreme position, such as its normal position, and when the motor is supplied with current over a second operating circuit, the mechanism is operated as required to move the switch to its other extreme position, that is, to its reverse position. Switch machines SM! and SM2 are made dependent upon each other intheir operations so that the two ends of the crossover 3 agree as to position. That is, the two switches of crossover 3 are related switches capable of being controlled by the same control circuit.

It'is to be pointed out that signals R2 and L2 constitute what is commonly referred to as a right and a left signal which are selectively governed by a single control circuit effective to establish either a right or a left control, that is, either a normal or a reverse control. It is to be further noted that signals RZA and L2 are used when the crossover 3 occupies its normal position and signal B2B is used for governing traffic moving from eastbound track ET to westbound track WT when crossover 3 occupies its reverse position. Again, it is noted that signals R4 and L4 constitute right and left signals. Hence, signals L2 and R2, and signals R4 and L4 constitute in each case what I have termed a trafiic governing unit capable of being controlled by a single control circuit. Since the two switches of crossover 3 are related switches, they also constitute a traffic governing unit capable of being controlled by a single control circuit. It follows, therefore, that this interlocking is unbalanced as to the switches and signals, there being one trafiic governing unit for the switches and two traflic governing units for the signals.

It is to be understood, of course, that my invention is not limited to this one track layout of an interlocking, but such layout is used to illustrate the invention because it is sufficient to show the principle of the apparatus embodying my invention. 7

Control of the switches and signals'of this interlocking is effected in part from a remote office DS through the medium of a remote control system utilizing apparatus located partly at the ofiice DS and partly at a station FS which station is preferably located adjacent the interlocking. As will appear more fully hereinafter, the

trafhc governing unit consisting of the two switches of crossover 3 is controlled and indicated over a control line circuit including a control line wire WI and a common line wire CO. Likewise the trafiic governing unit consisting of signals R2 and L2 is controlled and indicated over a control line circuit including a control line wire W2 and the common line wire CO. Also, the trafiic governing unit consisting of signals RA and L4 is controlled over another control line circuit including a control line wire and the common line wire CO, but this latter circuit is not shown in order to simplify the drawing since the latter line circuit and its related apparatus would be substantially a duplication of the control circuit including line wires W2 and CO and the apparatus associated therewith for controlling and indicating signals R2 and L2.

Office DS' and station F are provided each with a suitable source of alternating current and in the present embodiment of the invention, the

source of current at ofiice DS is a transformer Tl whose primary winding I0 is oonnectedto a generator, not shown, through the medium of the usual transmission line, and the source of current at station FS is a transformer T2 whose primary winding II is connected to the same generator through the transmission line. It follows that the alternating currents supplied by transformers TI and T2 are of the same frequency and are in phase. As an aid in the understanding of the invention, I shall consider that the connections for transformers TI and T2 are such that the terminals BX and CK of the secondary windings I2 and 13 of the two transformers are of corresponding relative polarity, That is to say, the terminals'BX of the two transformers become positivefand negative in polarity in step with each other, and likewise the terminals CX of the transformers become positive and negative in polarity in step with each other.

As a further aid in the understanding ofthe invention, I shall refer to the current supplied by a transformer when'its terminal BX is positive in potential with respect to its terminal CX as being the positive half cycle of the alternating current; and the current supplied by atransformer when its terminal CX is positive in potential with respect to its terminal BX as being the negative half cycle of the alternating current. To put it another way, a positive sending half cycle of current is supplied by a transformer during the half cycle itsterminal BX is positive in potential with respect to its terminal OK and a negative sending half cycle of current is supplied by a transformer during the half cycle its terminal CX is positive in potential with respect to its terminal BX. The manner whereby secondary windings I2 and I3 of transformers TI and T2, respectively, are connected to the different control circuits for supplying current thereto will appear as the specification progresses, but it is to be observed that the CX terminal of each transformer is connected permanently to the common line wire CO, such connections including wire 30 at office DS and wire 49 at station FS.

Referring to oflice DS, three manuallycontrolled means are provided, a switch lever 31'.- and two signal levers 2L and AL. As will appear shortly, lever 3L is used to control crossover 3, lever 2L is used to control signals R2 and L2 and lever 4L to control signals R4 and L4. In accordance with usual practice, switch lever SL is operable to either a normal position N or to a reverse position R, and each signal lever 2L and 4L is normally positioned at a mid position C and is operable to either a, left-hand position LH or to a'right-hand positionRI-I, Four circuit controlling contacts l4, l5, l6 and l! are opcratively connected to lever3L, as indicated by a dash line l8. These contacts, as well as other contacts operated by the other levers, are shown conventionally by a circle having placed therein a reference character indicating the position of the associated lever at which the contact is closed. For example, at a first or normal position N of lever 3L, contacts M and H are closed and at a second or reverse position R of the lever,-the contacts 15 and I6 are closed. Likewise, four circuit controlling contacts I9, 20, 2i and 22 are operatively connected to lever 2L, as indicated by a dash line 23, the arrangement being such that at the RH position of the lever contacts 20 and 2| are closed and at the LH position of the lever contacts I9 and 22 are closed.

In the present embodiment of my invention these manually controlled means at the office station are shown as manually operable levers, but it is to be understood that levers 3L, 2L and AL can be replaced by manually controlled relays whose front and back contacts replace the lever contacts shown in the drawing. When manually operable levers are used, such levers may be provided with the usual mechanical looking, or they may be of the usual push button type used in an all relay type of interlocking machine. When relays are used and such relays are the relays of a route type of interlocking, contacts I4 and I6 of lever 3L could be replaced by a front and back contact of a first switch control relay of a route network, and contact I I and I could be replaced by a front and back contact of a second switch control relay of the network. Again, if desired, contacts I4 and I! could be made two separate front contacts of the first switch control relay, and contacts I5 and It could be replaced by two separate front contacts of the second switch control relay. In like manner, the contacts of signal lever 2L can be replaced by contacts of manually controlled relays, and it is to be understood that my invention contemplates the use of manually controlled relays as Well as manually operable levers.

At ofi'ice DS, the control line circuit Wl-C'O used for controlling crossover 3 terminates in four branch circuits which are selectively closed by the contacts of switch lever 3L, and two of which branch circuits serve to supply current to the line circuit from the office current source and the other two of which branch circuits serve to receive current transmitted from the station cur rent source over the associated control line circuit. The first one of the sending branch circuits can be traced from terminal BX of transformer TI over an asymmetric unit 24, top winding of a relay LRP to be later described, contact I 4 of lever 3L and wire 26 to the line Wire WI; and the second sending branch circuit can be traced from terminal BX over asymmetric unit 21, lower winding 23 of relay LRP, lever contact I5 and wire 25 to line wire WI. Asymmetric units 24 and 21 are disposed reverse to each other and as here shown, asymmetric unit 24 is disposed to permit the positive half cycles of the alternating current of transformer TI to pass to line wire WI over the first sending branch circuit when lever 3L is at its normal position to close contact I4, and asymmetric unit 2'! is disposed to permit the negative half cycles of the alternating current to pass over the second sending branch circuit when the lever 3L is moved to its reverse position R to close contact I5. Of the two receiving branch circuits, the first one can be traced from line wire WI over wire 25, lever contact I1, winding of an indication relay 3NK, to be referred to later, and an asymmetric unit 23 to wire 30 which is connected to the common line wire CO. The second receiving branch circuit involves wire 26, lever contact I6, winding of an indication relay 3RK, an asymmetric unit 3I and wire 39. The asymmetric units 29 and 3I are disposed reverse to each other and are further so disposed that when lever 3L is at its normal position to close the first sending branch circuit for supplying the positive half cycles of the alternating current from transformer TI to the line circuit, the receiving branch circuit connected to the line circuit by lever contact I! includes asymmetric unit 29 which is disposed to block the flow of such positive half cycles of current; and at the reverse position of lever 3L when the second sending branch circuit is closed for supplying negative half cycles of the alternating current from transformer TI to the line circuit, the second receiving branch circuit connected to the line circuit at contact I6 of the lever includes asymmetric unit 3| disposed to block the flow of such negative half cycles of current. In other words, the arrangement of the asymmetric units and the selection efiected by the contacts of lever 3L are such that neither one of the receiving branch circuits associated with the control line circuit WICO can be energized by current supplied from the oifice transformer TI The indication relays 3NK and 3RK are magnetically biased relays which are picked up by current of one relative polarity only. For example, these relays as well as other magnetically biased relays to be referred to later may be of the type covered by the United States Letters Patent No. 2,203,888, granted June 11, 1940, to H. E. Ashworth for Electrical relay. Looking at relay 3NK, this relay is picked up by current flowing in the direction indicated by the'arrow placed on the relay and which direction corresponds to the forward direction for the asymmetric unit 29 included in the same receiving branch circuit. The contact member 32 of relay 3NK is biased both magnetically and by gravity to engage its back contact when the relay is deenergized, is held in the released position in case the relay is energized by current flowing in the direction opposite to that indicated by the arrow on the relay and is picked up to engage a front contact when the relay is energized by current flowin in the direction corresponding to that indicated by the associated arrow. In like manner, contact member 33 of relay 3RK is biased to the released position to engage a back contact when th relay is deenergized, is held in that position in case the relay is energized by current flowing in the relay winding in the direction reverse to that indicated by the arrow placed on the relay and is picked up to engage a front contact when the relay is energized by current flowing in the relay winding in the direction indicated by the associated arrow. The function of relays 3NK and 3RK as well as that of relay LRP, will appear when the operation of the apparatus is described.

The control line circuit W2CO also terminates in four branch circuits at the ofiice DS and which branch circuits are selectively closed by contacts of the signal lever 2L, and two of which branch circuits are used for sending control current from the oflice station current source, and the other two of which are used to receive indication current supplied to the line circuit from the station current source. A first sending branch circuit for control circuit W2-CO includes terminal BX of transformer TI, wire 34, asymmetric unit 35, contact I9 of lever 2L and wire 36 connected to the control line wire W2; and the second sending branch circuit involves terminal BX of transformer TI, wire 34, asymmetric unit 31, lever contact 20 and wire 36. Asymmetric units 35 and 31 are disposed reverse to each other, unit 35 being disposed to pass the positive half cycles of the alternating current supplied by transformer TI and unit 31 being disposed to pass the negative half cycles of the alternating current. Thus at the left-hand posi-- tion LH of lever 2L, contact I9 is closed and control current consisting of the positive half cycles of alternating current is supplied to the control line circuit'W2--CO, and at the right-hand position RH of lever 2L contact 2. is closed and control current consisting of the negative half cycles of the alternating current is supplied to the line circuit. A first one of the associated receiving branch circuits includes wire 36 connected to line wire W2, lever contact 22, winding of an indication relay ZLK, asymmetric unit 38, and wires 39 and 39 connected to the common line Wire 00. The second associated receiving branch circuit involves wire 36, lever contact 2|, winding of an indication relay ZRK, asymmetric unit 40 and wires 39 and 3. Asymmetric units-38 and 49 are disposed reverse to each other and the arrangement is further such that when lever 2L is set at its'LH position closing contacts l9 and 22, and positive half cycles of current from transformer T| are supplied to the control line circuit such current is blocked by asymmetric unit 38 of the closed receiving branch circuit; and when lever 2L is set at its RH position closing contacts 29 and 2| and negative half cycles of alternating current are passed from transformer TI to the control line circuit, such current is blocked by asymmetric unit 49 of the closed receiving branch circuit. The indication relays ZLK and 2RK are magnetically biased neutral relays of the same type as the relays 3NK and SRK and their description need not be repeated except to point out that contact member 4| of relay 2LK is picked up only when relay 2LK is energized by current flowing in the relay in the direction indicated by an arrow placed on the relay, and contact member 42 of relay ZRK is picked up only when that relay is energized by current flowing in the direction of the arrow placed on that relay. Also, it is to be observed that each relay ZLK and ZRK is picked up by current of the polarity passed by the asymmetric unit of the same receiving branch circuit. The function of relays ZLK and 2RK will also be taken up when the operation of the apparatus is described.

As stated hereinbefore, the apparatus and circuits associated with signal lever 4L for controlling signals L4 and R4 are not shown for the sake of simplicity since they are but a' duplication of those associated with signal lever 2L for controlling signals L2 and R2.

Referring now to station FS, the control line circuit Wl-CO terminates in four branch circuits, two of which are used for receiving and two for sending. A first receiving branch circuit includes wire 43 connected to line wire Wl, front contacts 44 and 45 of track relays 4TH and ZTR, respectively, back contact of contact member 46 of a reverse switch controlling relay 3RWR. to be referred to later, winding of a normal switch controlling relay 3NWR also to be referred to later, asymmetric unit 47, front contact 48 of a relay LR to be referred to later, and wire 49 connected both to the common line wire CO and to the terminal CX of transformer T2. The second receiving branch circuit includes wire 43, front contacts 44 and 45, back contact of contact member 59 of relay 3NWR, winding of relay 3RWR, asymmetric unit 5|, front contact 48 of relay LR and wire 49. Starting at terminal BX of transformer T2, a first one of the sending branch circuits associated with control line circuit W|-CO, includes wire 52, asymmetric unit 53, front contact 54 of a normal switch repeater relay 3NWP to be referred to later, front contact of contact member 59 of relay 3NWR, .front contacts 45 and 44 of track relays ZTR and 4TB, respectively, and wire 43 connected to line wire WI; and a second sending branch circuit extends from terminal BX over wire 52, asymmetric unit 55, front contact 51 of a reverse switch repeater relay 3RWP, front contact of contact member 46 of relay 3RWR, front contacts 45 and 44 and wire 43 to line wire WI. In these station branch circuits for the control line circuit W|-CO, it is to be noted that in the receiving branch circuits asymmetric units 41 and 5| are disposed reverse from each other, switch controlling relays 3NWR and 3RWR, which are biased neutral relays of the type hereinbefore described, are each interposed in the respective receiving branch circuit to be picked up by current of the polarity passed by the asymmetric unit of the same circuit and that these two receiving branch circuits are interlocked by each being controlled over a back contact of the relay of the other receiving branch circuit. Regarding the two associated sending branch circuits, the two asymmetric units 53 and 59 thereof are disposed reverse to each other, the two branch circuits are selectively closed over front contacts of the two switch repeater relays 3NWP and 3RWP, which are in turn controlled according to the position of the crossover 3 as will shortly be described, and are controlled over front contacts of the switch controlling relays 3NWR and SRWR. Also the arrangement is such that when the first receiving branch circuit effective to pass positive half cycles of current from transformer TI is closed, the first sending branch circuit effective to pass the negative at cycles of the current of transformer T2 is closed, and when the second receiving circuit effective to pass the negative half cycles of current from transformer TI is closed, the second sending circuit effective to pass the positive half cycles of the current of transformer T2 is closed. Consequently at the field station neither one of receiving branch circuits of the control line circuit W|--CO can be energized by current supplied from the station current source. Furthermore, the branch circuits are all governed over contacts of the two track relays 2TB and 4TB of the detector track sections associated with cross-over 3, and are further governed over a front contact 43 of a locking relay LR, relay LR being controlled by the approach, route and detector locking usually provided at such interlocking but which are not shown since such locking forms no part, of my present invention and would be in accordance with standard practice. 7 a

Switch controlling relays 3NWR and SRWR govern the operating circuits for switch machines SMI and SMZ for operating the crossover. When normal switch controlling relay 3NWR is picked up to close front contact 59, a normal operating circuit is formed which includes terminal BI of a suitable source of current, such as a battery not shown, front contact 59, wire 60, switch machine SMI and wire 62 to terminal Ci of the same source of current, and switch machine SMI is operated as required to move the associated track switch to its corresponding normal position. This operating circuit is extended from switch machine SMI, over wire 63, through switch machine SMZ and wire 64 to terminal CI of the current source, and switch machine SMZ is operated as required to move the corresponding end of the crossover to its normal position. When reverse switch controlling relay 3RWR is picked up to close front contact 65, a reverse operating circuit is formed which includes terminal Bl, front contact 65, wire $5, switch machine SMI and wire 62 to terminal Ci, and switch machine SM! is operated as required to move the corresponding end of the crossover to its reverse position. This reverse operating circuit is extended from switch machine SMl over wire 67, through switch machine SM2 and wire 84 to terminal Cl, and switch machine SMZ is operated as required to move its corresponding end of the crossover to the reverse position.

Switch repeater relays SNWP and BRWP are governed by the position of crossover 3 in any one of the several well-known ways, and as here shown relay 3NWP is provided with a circuit including terminal Bl, a contact 68 of a switch circuit controller operably connected to the switch at the west end of the crossover and moved to the position illustrated by the solid lines in the drawing when the respective switch is at its normal position, contact 69 of a switch circuit controller operably connected to the switch at the east end of the crossover and moved to the position illustrated by the solid lines at the normal position of the respective switch, winding of relay dNWP and terminal Cl. When the switches of crossover 3 are both at their reverse positions causing contact members 63 and 69 to be moved to the positions illustrated by the dotted lines in the drawing, a circuit is formed for relay SRWP, as will be readily understood by an inspection of the drawing. It follows that relay SNWP is picked up only when both ends of the crossover occupy their respective normal positions, and relay BRWP is picked up only when both ends of the crossover occupy their respective reverse positions. As explained hereinbefore, relays BNWP and 3RWP control the sending branch circuits of the control line circuit W|CO.

Referring to the control line circuit W2CO, this circuit also terminates in four branch circuits at the station FS, two of which are used for receiving current and two of which are used for sending current. A first receiving circuit includes wire 19 connected to line wire W2, back contact of contact member H of a signal controlling relay RHR, winding of a signal controlling relay LI-IR, asymmetric unit 72 and wire 49 connected to common line wire CO. The second receiving branch circuit include wire 18, back contact of contact member 73 of relay LI-IR, winding of relay RHR, asymmetric unit 14 and wire 49. A first sending branch circuit can be traced from terminal BX of transformer T2 over wire 52, asymmetric unit ?5, front contact 16 of a signal repeater relay LHP, front contact of contact member '13 of relay LHR and wire to line wire W2. The second sending branch circuit includes terminal BX of transformer T2, wire 52, asymmetric unit 'i'l, front contact E8 of a signal repeater relay RHP, front contact of contact member ll of relay REE and wire 19 connected to line wire W2. It is to be seen that of the receiving branch circuits at station FS associated with the control circuit WZ-CO, the first one is effective to pass the positive half cycles of current of transformer T1 and the second is effective to pass the negative half cycles of current of transformer Ti, and that each of the signal controlling relays LHR and RHR is effectively energized and picked up by current of the polarity passed by the associated asymmetric unit of the same branch circuit, relays LI-IR and Rl-IR being magnetically biased neutral relays of the type previously described, and each being picked up when eners c et gized by current flowing in the relay in the direction of an arrow placed on the relay. Also the two receiving branch circuits are interlocked by each including a back contact of the relay of the other circuit. In the sending branch circuits the asymmetric units 15 and 11 are disposed reverse to each other, and the two sending branch circuits are selectively governed by the signal repeater relays LHPand RHP and are also governed by the signal controlling relays LHR. and RI-IR. Furthermore, it is to be observed that the receiving branch circuits for the control circuit W2'CO are not energized by current supplied by the station transformer T2.

The signal controlling relays LHR and RHR govern the operating circuits of signals R2 and L2 through the medium of signalcontrol relays, there being one signal control relay for each of the signals. To be explicit, when relay LHR. is picked up a circuit is formed from terminal BI over front contact 19 of relay LHR, winding of a signal control relay L2H for signal L2, contacts and 8| of the switch circuit controllers for the crossover 3 and closed at the normal position of the crossover, and terminal CI of the current source, and relay L2H is picked up. As shown in the upper right-hand portion of the drawing signal control relay L2H when picked up to close front contact 83, completes a simple operating circuit for signal L2 and that signalis operated as .required to display a proceed indication. Furthermore, when signal control relay L2H is picked up to operate signal L2, signal repeater relay LHP i energized over an obvious circuit including front contact 84 of relay L2H. It is to be recalled that signal repeater relay LHP controls at its front contact 16 the first sending branch circuit for the associated control circuit W2CO. Consequently, when a control current consisting of positive half cycles of current of transformer TI is received at station FS, over the line circuit WZCO, the signal controlling relay LHR is picked up to cause energization of signal control relay L2H and that relay in turn controls the operating circuit of signal L2 and the energizing circuit for the signal repeater relay LHP which latter relay closes the sending branch circuit for supplying indication current consisting of negative half cycles of current from transformer T2 to the associated control circuit WZ-CO.

Again when signal controlling relay RHR is picked up, a circuit is formed for energizing signal control relays RZAH and RZBH, one or the other of the relays being energized according to the position of crossover 3. The circuit includes terminal BI, front contact 85 of relay RHR, winding of relay R2Al-I, contacts 86 and 81 of the switch circuit controllers for the crossover closed at the normal position of the crossover, and terminal Cl. In case crossover 3 is moved to its reverse position so that contact members 86 and 81 are moved to the positions illustrated by the dotted lines in the drawing, then this circuit controlled by relay RHR is com- Dleted through winding of signal control relay RZBH, and contacts 86 and 891 to terminal Cl. As shown adjacent signal R2, signal control relay RZAH when picked up completes at its front contact 88 an obvious operating circuit for signal RZA. and that signal is operated as required to display a proceed indication; and signal control relay RZBH when picked up completes at its front contact 89 an obvious operating circuit for signal B2B, and that signal is operated as required to display a proceed indication.

When either relay RZAH is picked up to close front contact 9|, or relay R2BI-I is picked up to close front contact 92, signal repeater relay RHP is energized and picked up to control at its front contact 18 the second sending branch circuit for the control circuit W2- -CO. Consequently, when a control current consisting of the negative half cycles of current from transformer TI is received from the control line circuit W2- CO at station FS, signal controlling relay RHR is picked up to control relay RZAH or RZBH depending upon the position of the crossover, and these relays in turn cause operation ofsignal RZA or B2B and energization of signal repeater relay RHP, which latter relay then controls the corresponding sending branch circuit. The signal control relays L2H, RZAH and R2BI-I would, of course, be controlled by trafiic conditions but such traffic control is not shown since it forms no part of my invention and would be in accordance with usual practice.

In describing the operation of the apparatus I shall first assume that the switch lever 3L is set in its normal position N and signal levers 2L and 4L are set in their mid positions C. Lever contacts l4 and IT are closed in the normal position N of lever 3L and consequently each half cycle that terminal ZX of transformer TI is of positive relative polarity current flows through the sending branch circuit comprising asymmetric unit 24, winding of relay LRP and contact l4, thence over line wire W! to station FS,

through the station receiving branch circuit including normal switch controlling relay SNWR and asymmetric unit 41 to line wire CO and back over the common line wire CO to terminal CX of transformer TI. Relay 3NWR is effectively energized and picked up by such control current comprising the positive half cycles of the current from transformer TI and relay 3NWR in picking up causes operation of crossover 3 to its normal position in the manner previously described. Switch repeater relay 3NWP is effectively energized in response to the normal position of the crossover to close the station sending branch circuit including asymmetric unit 53 so that each half cycle that terminal OX of transformer T2 is of positive relative polarity current flows over the common line wire CO to the Ofi'iCB DS, through the ofiice receiving branch circuit comprising asymmetric unit 29, indication relay 3NK, lever contact i1 and wire 26 to line wire WI, back to station FS and through the sending branch circuit including front contact of contact member of relay 3NWR, front contact 54 of relay 3NWP, asymmetric unit 53 and to terminal BX of transformer T2. Such indication current comprising the negative half cycles of the current from transformer T2 causes relay 3NK to be picked up, and relay 3NK on picking up to close the front contact of its contact member 32 completes a local indication circuit easily traced for a normal switch indication lamp 3N and that lamp is illuminated to indicate the normal position of crossover 3. It is to be seen therefore that crossover 3 is continuously controlled and indicated over the control circuit including line wires WI and CO, the control current consisting of the positive half cycles of the alternating current supplied by transformer Tl at the oflice andthe indication current consisting of the negative half cycles of the alternating current as supplied by thetransformer T2 at the station. It is to be noted that the relay LRP at the oflice station is energized and picked up by such control currentbut operation of relay LRP at this time performs no particular function.

I shall next describe the operation that follows the moving of lever 3L to its reverse positionR to control crossover 3 to its reverse position. At the reverse position R of lever 3L, contacts l4 and I1 are opened and contacts I5 and I6 are closed. The opening of contact It causes normal switch controlling relay 3NWP to be .deenergized. The closing of contactlfi causes a control current consisting of negative half cycles of verse position.

current from transformer TI to flow over the common line wire CO to station FS, through the station receiving branch circuit including 1 asymmetric unit 5| and reverse switch controlling relay 3RWR, thence back over line wire WI to the office through the office sending branch circuit comprising lever contact l5, lower winding 2B of relay LRP and asymmetric unit 21 and to terminal BX of transformer TI. This control current consisting of negative half cycles of current supplied by transformer Tl causes the switch controlling relay 3RWR to be picked up and the reverse operating circuit for crossover 3 to be closed so that crossover 3 is operated to its re- At the reverse position of crossover 3 switch repeater relay 3RWP is picked up to close the corresponding station sending branch circuit so that the positive half cycles of current from transformer T2 flow through the sending branch circuit including asymmetric unit 56 and front contact 51 of relay SRWP, thence over line wire Wi to the oflice, through the office receiving branch circuit comprising contact l6, relay 3RK and asymmetric unit 3|, and back over the common line wire CO to terminal CX of transformer T2. Relay 3RK is picked up by this indication current consisting of the positive half cycles of the current from transformer T2, and relay SRK completes at the front contact of its contact member 33 an indication circuit for indication lamp 3R, and that lamp is illuminated to indicate the reverse position of the crossover.

It is to be noted that while the switches of crossover 3 are in transit from the norrna1 to the reverse position, both switch repeater relays 3NWP and 3RWP are released and no indication current is received at the office, with the result both indication relays 3NK and 3RK are released. Relay LRP however is energized and picked up by the control current and a local indication circuit is formed from terminal BX of transformer TI over back contacts of the contact 7 members 32 and 33 of relays 3NK and SRK, re-- spectively, front contact 94 of relay LRP, lamp 'the crossover 3 is electrically locked against movement because the control circuit W l--CO is held open at the station. With circuit Wl-CO held open at the station, both the control and indication currents are interrupted with the result that all the relays LRP, SRK and 3NK are released. Under this condition of the relays associated with lever 3L, a circuit is formed including the back contacts of contact members 32 and 33, back contact 95 of relay LRP and lamp OS, and lamp OS is illuminated to indicate the presence of a train in one or both of the detector track sections. Also a circuit is formed fora lamp LO at back contact 93 of relay LRP to provide a special switch locked indication.

Again under traffic conditions that would cause relay LR at the station to be deenergized to open its front contact 48, the station receiving branch circuits are open to electrically lock crossover 3 against operation. Relay LRP is now deenergized closing its back contact 93 to cause lamp L to be illuminated as explained above to indicate the switch locked condition. When relay LR is thus released causing both switch controlling relays 3NWR and 3RWR to be released, the associated sending branch circuits are held open at the station with the result that no indication current is supplied and both indication relays SNK and 3RK are released with the result that the lamp OS is also illuminated when relay LR is released to provide an indication of the presence of a train in the vicinity of the crossover 3.

The operation following a movement of lever 3L from its reverse position R to its normal position N to effect a movement of the crossover 3 from its reverse to its normal position is similar to that following the movement of lever 3L to its reverse position and such operation of the apparatus to move the crossover back to its normal position will be readily understood by an inspection of the drawing taken in connection with the description of the operation of the apparatus to move the crossover to its reverse position.

At the mid position C of signal lever 2L, the respective lever contacts are all open and consequently the control line circuit W2CO is deenergized. Under such deenergized condition of the control circuit W2-CO, both indication relays ZRK and 2LK are released and a local indication circuit is formed from terminal BX of transformer Tl over back contacts of the contact members 52 and 4| of relays ZRK and 2LK, respectively, lamp 2S and to terminal CX, and lamp 28 is illuminated as a stop position indication for the signals controlled by lever 2L.

I shall next assume that with switch lever 3L set at its normal position to effect the normal position of crossover 3, the signal lever 2L is moved to its left-hand position LH to control signal L2. At the LH position of lever 2L, contacts l9 and 22 are closed and each cycle that terminal BX of transformer T! is of positive relative polarity, current flows through the office sending branch circuit comprising asymmetric unit 35 and contact I9, line wire W2, through the station receiving branch circuit comprising signal controlling relay LHR and asymmetric unit 12 to the common line wire CO and back to terminal CX of transformer Ti. Relay LHR is picked up by such control current consisting ofthe positive half cycles of the current supplied by transformer T I. Relay LHR on picking up con trols relay L2H to cause operation of si nal L2 and energization of signal repeater relay LHP in the manner described hereinbefore. Relay LI-lIP when picked up to close its front contact '68 completes the station sending branch circuit and each half cycle that terminal CX of transformer T2 is of positive relative polarity, indication current flows over the common line wire CO, through the office receiving branch circuit comprising asymmetric unit 38, indication relay ELK and lever contact 22, and thence over the line wire W2 and the station sending branch circuit comprising front contact of the contact member 13 of relay LHR, front contact 75 of relay LHP and asymmetric unit l to the terminal BX of transformer T2. Relay 2LK is energized and picked up by this indication current consisting of the negative half cycles of the current supplied from transformer T2, "and relay ZLK on picking up to close the front contact of its contact member 4! completes a local circuit for indication lamp LES and that lamp is illuminated to indicate that signal L2 is controlled to its proceed position. It follows that signal L2 is continuously controlled and indicated over the line circuit W2CO in response to signal lever 2L moved to its LH position, the control current consisting of the positive half cycles of the alternating current from transformer TI and the indication current consisting of the negative half cycles of the alternating current from trans former T2.

In the event signal lever 2L is moved to its RH position when crossover 3 is normal, the closing of contacts 20 and 2| of lever 2L controls signal RZA to its proceed position. During each half cycle that terminal CX of transformer TI is of positive relative polarity, current fiows over the common line wire CO to the station, through the receiving branch circuit comprising asymmetric unit 14 and signal controlling relay RHR, back over line wire W2 to the office and through the sending branch circuit comprising contact 20 and asymmetric unit 31 to terminal BX of transformer Tl. Relay RHR is eifectively energized and picked up by this control current consisting of the negative half cycles of the current supplied from transformer TI, and relay RHR on picking up closes front contact to control relay R2AH and that relay in turn causes signal REA to be operated to a proceed position, and signal repeater relay RI-lP to be energized. Relay RI-IP when picked up closes front contact i8, closing the corresponding station sending branch circuit so that each half cycle that terminal BX of transformer T2 is of positive relative polarity, current flows through the sending branch circuit comprising asymmetric unit If and front contact 78 of relay RHP, over the line wire W2 to the OffiCB, through the office receiving branch circuit comprising contact 2|, relay 2RK and asymmetric unit 43, and thence over the common line wire CO to terminal CX of transformer T2. Relay ERK is picked up by such indication current consisting of the positive half cycles of the current supplied by transformer T2, and relay 2RK on picking up to close the front contact of its contact member 42, completes a local indication circuit for lamp R28 and that lamp is illuminated to indicate that signal R2A is controlled to its proceed position. In the event crossover 3 is at its reverse position when signal lever 2L is moved to its RH position the relay RZBH is selected and signal R23 is controlled to a proceed position in response to the picking up of relay RHR and this position of signal B2B is indicated by the illumination of lamp RES in the manner explained above in connection with the operation of signal RZA.

It follows that signal R2A or RZB as the case may be is continuously controlled and indicated over the control circuit W2-CO when lever 2L is moved to its RH position, the control current consisting of negative half cycles of the alternating current from transformer TI and indication current consisting of positive half cycles of aiternating current from transformer T2.

As stated hereinbefore, the signals LE and R4 are controlled and indicated by signal lever 4L and an associated control circuit in the same manner as signals L2 and R2 are controlled by ratus.

signal lever 2L and the associated control circuit W2---CO.

Advantages of a remote control system embodying my invention include the continuous control and indication of a traffic governing unit over a single line circuit and which control and indication is accomplished without critical time values in the operation of the respective appa- Also extra circuits and apparatus are not required because of anunbalanced condition of an interlocking layout. Manual control can be efiected by levers or by relays. Special switch in transit and switch locked indications are provided for a switch as well as an indication of a train in the vicinity of the switch. Use of magnetically biased neutral relays provides additional assurance that a control relay is not inadvertently energized and pickedup by current of the reverse polarity. It is to be pointed out that in using biased neutral relays of the type here described, the asymmetric units in certain of the branch circuits may be omitted if desired and proper selection efiected by the biased relays alone.

Although I have herein shown and described but one form of remote control system embodying my invention, it is understood that various changes and modifications may be made therein within the scope of the appended claims without departing from the spirit and scope of my invention.

Having thus described my invention, what I claim is:

1. A remote control system for railways comprising, an oflice provided with a manually controlled means and an indication means each operable to a first and a second condition, a station provided with a traffic governing unit operable to a first and a second position, a source of alternating current at the office and at the station, a control line circuit extending between said office and station and terminating in two sending and two receiving branch circuits at each such location, said sending branch circuits at each location interposed between the current source and said line circuit and efiective when closed, one to pass the positive half cycles of current only and the other to pass the negative half cycles of current only of the associated current source, said receiving branch circuits at each location connected to said line circuit and each including a relay characterized by being operated by current of one polarity only and the two relays at a location being arranged for operation by currents of opposite polarities, means including contacts of the station relays to operate said traffic governing unit to its first or second position according to which relay is operated, means including contacts of the oflice relays to operate said indication means to its first or second condition according to which relay is operated, means including contacts governed by said manually controlled means to selectively close the oflice sending and receiving branch circuits to send positive half cycles and effectively receive only negative half cycles of alternating current at said first condition of the manually controlled means and to send negative half cycles and effectively receive only positive half cycles of alternating current at said second condition of the manually controlled means, and means including contacts governed by said trafilc governing unit to selectively close the station sending branch circuits to send negative half cycles of current when positive half cycles of current are received and to send positive half cycles of current when negative half cycles of current are received.

2. A remote control system for railways, comprising an ofiice provided with a manually controlled means and an indicating means each operable to a first and a second condition, a station provided with a traffic governing unit operable to a first and a second position, a source of alternating current at the office and at the station, a control line circuit extending between said office and station and terminating in two sending and two receiving branch circuits at each such location, said sending branch circuits at each such location interposed between the current source and said line circuit and effective when closed one to pass the positive half cycles of current only and the other to pass the negative half cycles of current only of the associated current source, said receiving branch circuits at each location connected to said line circuit and each including a relay characterized by being operated by current of one polarity only and the two relays at a location being arranged for operation by currents of opposite polarities, means including contacts of the station relays to operate said trafiic governing unit to its first or second position accordin to which relay is operated, means including contacts of the ofiice relays to operate said indication means to its first or second condition according to which relay is operated, means including contacts governed by said manually controlled means to selectively close the office sending and receiving branch circuits to send positive half cycles and efiectively receive only negative half cycles of alternating current at said first condition of the manually controlled means and to send negative half cycles and effectively receive only positive half cycles of alternating current at said second condition of the manually controlled means, means including contacts of said relays at the station to interlock the station receiving branch circuits and permit only one relay to be operated at a time, and means including contacts governed by said traflic governing unit to selectively close the station sending branch circuits to send negative half cycles of current when positive half cycles of current are received and to send positive half cycles when negative half cycles are received.

3. A remote control system for railways comprising, an office having a manually controlled means and an indicating means each operable to a first and a second condition, a station having a traffic governing unit operable to a first and a second position, a source of alternating current at said ofiice and at said station, a control line circuit including a pair of line wires extending between said office and station, two sending branch circuits at each such location one effective to pass only the positive half cycles and the other effective to pass only the negative half cycles of alternating current, two receiving branch circuits at each such location each including a biased relay characterized by being picked up by current of one polarity only, means including contacts of the station receiving branch circuit relays to operate said trafiic governing unit to its first or second position according to which relay is picked up, means including contacts of the ofilce receiving branch circuit relays to operate the indicating means to its first or second condition according to which relay is picked up, means including contacts governed by said manually controlled means to selectively connect the ofiice current source to said line circuit through the office sending branch circuits according to the first and second condition of the manually controlled means and to selectively connect the oifice receiving branch circuits across the control circuit according to the first and second condition of the manually controlled means, and means including contacts governed by the trafiic governing unit to selectively connect the station current source to thecontrol circuit through the station sending branch circuits according to the first or second position of the traific governing unit.

4. In apparatus for use in a remote control system for railways including an ofiice provided with 1 a manually controlled means and an indicating means each operable to awfirst and a second condition, a station having a traffic governing unit operable to a first and asecond position, a source of alternating current at said oifice and at said station and a line circuit extending between such locations and terminating at each location into two sending and two receiving branch circuits of which the sending branch circuits at each location have interposed therein asymmetric units so that one passes the positive half cycles only and the other the negative half cycles only of the source of the same location, the combination comprising, magnetically biased relays characterized by being picked up by current of one polarity only interposed one in each of said receiving branch circuits, said two relays at each location arranged .to be picked up by currents of opposite polarities, means including contacts of the station relays to operate the traffic governing unit to its first and second position according to the relay picked up, means including contacts of the ofiice relays to operate the indicating means to the first or second condition according to the 'relay picked up, meansincluding contacts of said manually controlled means'to selectively connect said ofiice current source to said line circuit through the ofiice sending-branch circuits and to selectively connect the oifice. receiving branch circuits across the line circuit, means including contacts governed'by the traffic governing unit and contacts governed by the station relays to selectively connect the station current source to the line circuit through the field station sending branch circuits, andmeans to connect the station receiving branch circuits across the line circuit. PAUL. H. CRAGO. 

